Short Message Service (SMS) messaging is a form of communication supported by most mobile telephone service providers and widely available on various networks including Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), and third generation (3G) networks. SMS messaging is described in GSM specifications such as GSM specification 03.40 “Digital cellular telecommunications system (Phase 2+); Technical realization of the Short Message Service” and GSM specification 03.38 “Digital cellular telecommunications system (Phase 2+); Alphabets and language-specific information.”
In general, SMS messages from a sender are transmitted to a Short Message Service Center (SMSC) which provides a store-and-forward mechanism for delivering the SMS message to one or more recipients. An SMS message from a sender may contain an SMS header including a destination telephone number and a payload containing the text portion of the message. Typically, the payload of an SMS message is limited by the supporting network infrastructure and communication protocol to no more than 140 bytes which translates to 160 7-bit characters based on a default 128-character set defined in GSM specification 03.38, 140 8-bit characters, or 70 16-bit characters for languages such as Arabic, Chinese, Japanese, Korean, and other double-byte languages.
Due to payload limitations, a long message having more than 140 bytes or 160 7-bit characters may be delivered as separate SMS messages. In some cases, the SMS infrastructure may support concatenation allowing a long message to be sent and received as multiple concatenated SMS messages. In such cases, the payload of each concatenated SMS message is limited to 140 bytes but also includes a user data header (UDH) prior to the text portion of the message. The UDH contains segmentation information for allowing the recipient to reassemble the multiple concatenated SMS messages into a single long message.
The text content of an SMS message may contain alphanumeric characters as well as iconic characters (e.g. smiley characters) made up of a combination of standard punctuation marks such as a colon, dash, and open bracket for a smile. Iconic characters may be selected by the sender, sent as punctuation equivalents, and deciphered back into iconic representations at the recipient. The text content of an SMS messages also may include certain classes of hidden messages reserved for use by network operators and push e-mail clients to control data or events on the terminal.
Multimedia Messaging (MMS) technology provides capabilities beyond those of SMS and allows users to send and receive multimedia messages including graphics, video and audio clips. Unlike SMS, which depends primarily on the underlying wireless network technology (e.g. GSM, CDMA, TDMA), MMS relies on Internet Protocol (IP) technology and is designed to work with mobile packet data services such as General Packet Radio Service (GPRS) and Evolution Data Only/Evolution Data Optimized (EV-DO).
In addition to full-length (e.g., 10-digit) telephone numbers, a common short code (CSC) also can be used as a destination to address SMS and/or MMS messages. A CSC is a shorter telephone number ranging from four to six numeric digits and is commonly used in the context of mobile services. While a CSC is easier to memorize than a full-length telephone number, to make it even easier to remember, the CSC may be designed or chosen as a mnemonic short code including a word or other pattern of letters and numbers that map to the numbers of a standard 12-key telephone keypad (1=none, 2=ABC, 3=DEF, 4=GHI, 5=JKL, 6=MNO, 7=PQRS, 8=TUV, 9=WXYZ, *=none, 0=none, #=none). When using a standard 12-key telephone keypad, a user may address an SMS or MMS message simply by pressing the keys associated with each letters and/or number of the mnemonic short code.
Some mobile computing devices such as smart phones enable users to compose SMS and MMS messages using a full QWERTY keyboard. For many of such devices, however, the keys of the QWERTY keyboard do not provide standard 12-key telephone keypad functionality. Consequently, addressing SMS or MMS messages when using a full QWERTY keyboard requires the user to know the actual numeric digits of the CSC. This can be cumbersome especially in cases where the user knows a mnemonic short code but has to look at the layout of a standard 12-key telephone keypad to get the numeric digits of the CSC corresponding to the letters of a word before addressing the message.
Accordingly, there is a need for improved message addressing techniques for a mobile computing device.